In recent years, technologies for producing minute structures have been developed, and also, it has been required to evaluate shapes and mechanical properties of the produced minute structures on site.
In the related art, usage of a focused ion beam (hereinafter, referred to as an FIB) to process minute samples in a level of micro meters (μm) is known. There is a method in which a sample is cut by the FIB, a sample stage with the sample placed thereon is rotated, and a cut surface is observed with a scanning electron microscope (hereinafter, referred to as an SEM) with the sample on the sample stand (see JP-A-2008-039521). In addition, an ion beam processing apparatus capable of processing minute rotating bodies with the FIB is known (see JP-A-2008-191120).
Evaluation of properties described in this specification means evaluation of mechanical properties such as bending, torsion, compression, heating and cooling, and fatigue. As an apparatus for evaluating a tension property of a minute sample, an apparatus that accurately measures local stress and distortion by installing a small sample in a sample chamber of an SEM and performing SEM observation on the minute sample while applying tension force to the sample to detect variations in shapes of crystal particles that form the minute sample has been disclosed (see JP-A-H04-135079).
In a case in which an evaluation target is a silicon semiconductor device, for example, an element as a focused portion is typically formed in the vicinity of one surface of a silicon substrate in many cases. Therefore, the object of evaluating configurations of the focused portion can be achieved by processing and observing only one surface of the evaluation target. However, in a case of a natural product, such as a mineral, or an artificial structure in which focused portions are dispersed in the entire target, the focused portions do not necessarily gather on one surface, and it is desirable to process and observe the entire outer periphery of the target. However, it is difficult to realize such processing and observation by the techniques in the related art disclosed in JP-A-2008-039521, for example.
Although tension evaluation is one of the most important items of mechanical evaluation, other properties such as torsion, bending, and compression are also as important items of the evaluation as the tension, and these properties also require evaluation. However, it is difficult to realize the evaluation by the technique disclosed in JP-A-2008-191120.
A description will be given of how important it is to evaluate bending of a sample, as an example of evaluation of another property. Generally, it is considered that mechanical properties of a large member in a level of several tens of mm do not coincide with mechanical properties of a member in a level of μm even though the members are made of the same material, and it is considered that properties unique to the small sample appear. For example, a prism of silicon single crystal in a level of mm (for example, a quadrangular prism with a size of 5 mm×5 mm×100 mm) is significantly brittle. If a so-called three-point bending test in which a vertical load is applied to both ends and the center is conducted thereon, the sample breaks in a brittle manner almost without bending. However, a small quadrangular prism of the same silicon single crystal with a size of 5×μm×5 μm×100 μm, for example, exhibits an elastic characteristic. In recent years, minute structures in a level of μm, such as components of microelectromechanical systems (MEMSs), have been produced as described above. However, sufficient mechanical evaluation of such small samples has not been conducted under the current situations. From such a viewpoint, JP-A-2008-191120 does not describe that it is possible to evaluate mechanical properties other than the tension property.
In a case in which an evaluation target sample has an elongated prism shape with a cross section of 5 μm×5 μm and a length of several mm, for example, there is a high risk that the sample is damaged while producing the sample outside the evaluation apparatus and mounting the sample on the evaluation apparatus. In addition, there is also a risk that the production of the sample outside the evaluation apparatus causes variations in mechanical properties due to chemical transformation such as deformation and oxidation. Thus, it is advantageous to produce a sample with a diameter of approximately 1 mm, which can be handled with human hands, in advance, to install the sample on an evaluation apparatus, to process the sample into a small sample for property evaluation inside the evaluation apparatus, and to evaluate the small sample there. From this viewpoint, JP-A-2008-191120 includes a description about evaluation of a tension property of a sample inside an SEM. However, JP-A-2008-191120 does not disclose a technique of producing a sample within the same evaluation apparatus and evaluating the sample there.
Furthermore, JP-A-H04-135079 includes a description about FIB processing in a cantilevered state as means for processing a material into a sample. However, JP-A-H04-135079 does not disclose a technique of evaluating configurations and properties of the outer periphery of the processing target.